1. Field of the Invention
The present invention relates to a fuel cell system and its control method. More particularly, it relates to the improvement of a technology for supplying and discharging various reactant gases to and from a fuel cell.
2. Description of Related Art
In general, a fuel cell (e.g., a polymer electrolyte fuel cell) is constituted by laminating a plurality of cells, each of the cells including an electrolyte held between separators. Moreover, a fuel cell system is constituted of, in addition to such a fuel cell, a piping system for supplying and discharging a reactant gas (a fuel gas or an oxidizing gas) to and from the fuel cell, an electric power system which charges and discharges electric power, a control system which generally controls the whole system and the like.
As the fuel cell system including such a fuel cell, for example, a system or the like is known in which a fuel gas (hydrogen gas) supply system is provided with a variable regulator, so that the set pressure of the fuel gas can be adjusted and controlled (e.g., see Patent Document 1).
[Patent Document 1] Japanese Patent Application Laid-Open No. 2004-139984